linux-aura: Switch between tabs on wheel scroll.

BUG=318873
R=erg@chromium.org, sky@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/65653003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236084 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236084